problems in natural convection

nabeel

hi, i am simulating quenching of heated cylinder in oil with natural convection. i want to ask four question 1.what is effect of g and operating density in opersting condition.what density and temperature should i use to get sonverged solution. 2.mr Ra is < 10e8 suold i use turbulence model 1equ or two equ. 3.in manuual it is mentioned that u use pressure p' in ur simulation.what this p' means. 4.during my simulation my monitors show on heated cylinder wall temp 325 this is temp on which i initialised my simualtion.but actually my temeprature is 1473 and it should fall with time in transient anlysis rather that it increase. can anbody help in this regard. nabeel